You shouldn't be yelling at your boss's boss's boss in a large company forum. That's rank insubordination, and easily punishable with firing. Hell it could be punished with much worse than insubordination in other kinds of organizations; imagine a private yelling at a general when the entire corps is being reviewed.
Companies are indeed hierarchical, and sometimes it feels like people forget that. You can indeed be fired at any time, and this is exactly the kind of situation you can put yourself in to have it happen to you.